Garcinia acid comprising (−)hydroxycitric acid (HCA), its lactone, and citric acid occurs in the fruit rind of Garcinia species (Garcinia cambogia, G. Indica, G. atrovirdis). In India the fruit is known by several local names (e.g., Kokum, Kodam Pulli, Uppige Hulli, etc.), and is used as a souring agent for pork and fish dishes. Traditionally, the extract of the fruit rind is used to improve digestion and in cooking, for the preparation of curries. The fruit rind of Garcinia is a rich source of (−)hydroxycitric acid, its lactone (10 to 30%), and citric acid.
(−)Hydroxycitric acid prevents the conversion of excess carbohydrates to fatty acids by inhibiting the actions of cytoplasmic (cytosolic) ATP-citrate lyase enzyme (D. Cloutre and M. E. Robenbaum, 1994, The Diet and Health Benefits of HCA) which plays key role in the conversion of carbohydrates to fatty acids and cholesterol (Sullivan et al., 1973, Lipids, 9:121,129).
Lewis et al., first isolated the lactone of (−)hydroxycitric acid from Garcinia cambogia. Pure (−)hydroxycitric acid is not stable and is converted to the more stable lactone form during processing. The free acid is stabilized by converting it into a salt form (e.g., sodium, potassium, calcium and zinc) by reacting the free acid with the respective base. Free (−)hydroxycitric acid can then be released when the salt is dissolved in an acid.
Some HCA compounds are known in the art. By way of example, EP 866137 relates to the preparation of calcium salt of HCA. However, since the calcium salt is insoluble in water, it is not preferred in formulating some products. As another example, U.S. Pat. No. 5,536,516 (Moffett et al.) describes a method to produce a liquid concentrate of HCA and its lactone, containing high concentrations of lactone compared to free HCA. However, this liquid HCA is not preferred because of its acidic nature and sour taste.
There is also described the preparation of soluble salts of (−) hydroxycitric acid. For example a tri-potassium salt of HCA was prepared by Lewis et al., (Methods in enzymology, vol. XIII, pp. 613–619 (Oct. 1, 1969), a soluble magnesium salt of HCA is described in U.S. Pat. No. 6,221,901 (Shrivastava et al.), and a soluble sodium and potassium salt of HCA is described in U.S. Pat. No. 6,395,296 (Balasubramanyam et al.). The recommended daily intake (RDI) of calcium, potassium, magnesium and zinc element is 1000 mg, 3500 mg, 400 mg and 15 mg respectively, and exceeding these amounts may create a risk of toxicity. Therefore, when these salts are used as individual salts (one metallic element in a given salt) there is risk of toxicity based on exceeding the RDI for the particular metallic element in the salt.
Accordingly, a need exists for other HCA salts and compositions containing the same.